Naslov
Thermosalient shuttle: N '-2-propylidene-4- hydroxybenzohydrazide

Autori
Skoko, Željko ; Popović, Jasminka ; Popović, Dean

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Acta Crystallographica Section A / - , 2015, S455-s455

Skup
29th European Crystallographic Meeting

Mjesto i datum
Rovinj, Hrvatska, 23.08.2015. - 30.08.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
thermosalient crystals

Sažetak
Systems providing mechanical response to external stimuli (heat or light) are rapidly becoming one of the focuses of material science investigations, since these materials are very promising in the sense of conversion of thermal (or light) energy into mechanical work on the nanoscale. One class of such materials are thermosalient
÷mÿùø÷ú ù c 􀀀ø÷ c

ý c÷ÿ  jumping crystals ƒ . These materials, when heated or cooled, undergo a sudden and sharp topotactic phase transition. During the transition, the crystals experience a change in their shape, as well as in the size of the unit-cell, that is so energetic that crystals literally jump off the stage to distances several times bigger than their dimensions [1]. It was reported [2] that N'-2- propylidene-4-hydroxybenzohydrazide behaved similarly as the jumping crystals. This system exhibited three polymorphic modifications (I, II and III), all having the same polar space group Pna2 1 , with the phase transitions I to II and III to II reported as topotactic. It was also reported that during the irreversible phase transition from I to II single crystals of the phase I were violently disintegrated into single crystal fragments of the phase II (without jumping), while in the reversible phase transition III to II the periodicity along the polar axis expanded (approximately 14%) and the integrity of the single crystals was preserved, i.e. no movement of crystals was observed. Our measurements showed a somewhat different behaviour. During the irreversible phase transition from I to II some of the crystals did indeed disintegrate into smaller fragments, but a large number remained intact ÷juým piúnög aÿll ar÷oumn d øco÷ver a􀀀la
rgeøý 9disctaù núcme÷s (:seÿvöe÷raøl 􀀀cùm) ; . Also, during the reversible phase transition II to III, and III to II, crystals exhibited the jumping behaviour, perhaps somewhat weaker than during the phase transition I to II. This is in contrast to the statements reported previously. We performed detailed structural and mechanical measurements, with special emphasis on the strain evolution in the crystal lattice during heating/cooling and on basis of that propose a new mechanism for jumping crystals phenomenon in this system.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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